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.TH getdns_hostname 3 "@date@" "getdns @version@" getdns
.SH NAME
.B getdns_hostname, 
.B getdns_hostname_sync
-- get hostname by address

.SH LIBRARY
DNS Resolver library (libgetdns, \-lgetdns)

.SH SYNOPSIS
#include <getdns.h>

getdns_return_t 
.br
.B getdns_hostname
(getdns_context *context,
.RS 3
getdns_dict *address,
.br
getdns_dict *extensions,
.br
void *userarg,
.br
getdns_transaction_t *transaction_id,
.br
getdns_callback_t callbackfn)
.RE

getdns_return_t 
.br
.B getdns_hostname_sync
(getdns_context *context,
.RS 3
getdns_dict *address,
.br
getdns_dict *extensions,
.br
getdns_dict **response)
.RE

.SH DESCRIPTION

.LP
The getdns_hostname(3) and getdns_hostname_sync functions provide public entry points into the getdns API library to retrieve the host name given an address.

.HP 3
.I context
A pointer to the previously created DNS context that is to be used with this DNS request. see getdns_context (3)

.HP 3
.I address
a getdns_dict structure containing two names: address_type (whose value is bindata and is either "IPv4" or "IPv6") and address_data whose value is bindata

.HP 3
.I extensions
extensions for this request, NULL if no extensions, see libgetdns (3) for a detailed description of extensions

.HP 3
.I userarg
returned to the callback function untouched, can be NULL

.HP 3
.I transaction_id
populated by the API and used to identify the callback (for example to getdns_cancel_callback), can be NULL, set to 0 if the function fails

.HP 3
.I callbackfn
non-NULL pointer to a callback function defined by the application, typically
used to process the response. Only the asynchronous signature accepts a
callback function, the synchronous signature does not include a callback.  See
libgetdns (3) for a more detailed discussion of callback functions.

.HP 3
.I response
A getdns_dict type is returned in response and always contains at least three names: replies_full (a list containing the DNS response as binary data), replies_tree (a list containing the parsed DNS response data) and status (an int).  The storage associated with this must be freed by a call to getdns_free_sync_request_memory (3).

.HP
.SH "RETURN VALUES"

Upon successful completion the functions return
.B GETDNS_RETURN_GOOD
, otherwise the following error values are returned:

.LP
.B GETDNS_RETURN_BAD_CONTEXT 
if the context pointer is invalid or the context has internal deficiencies
.LP
.B GETDNS_RETURN_BAD_DOMAIN_NAME
if the domain name passed to the function is invalid
.LP
.B GETDNS_RETURN_EXTENSION_MISFORMAT
if the data type specified in one or more of the extensions does not match the specifications
.LP
.B GETDNS_RETURN_GENERIC_ERROR
if some problem was encountered in the function not addressed by one of the more
specific return codes
.LP
.B GETDNS_RETURN_INVALID PARAMETER 
if one or more parameters has an invalid value
.LP
.B GETDNS_RETURN_MEMORY_ERROR
if unable to allocate the memory required
.LP
.B GETDNS_RETURN_NO_SUCH_EXTENSION
if one or more of the strings specified in the extensions are not valid

The values of status included in the response parameter are:

.LP
.B GETDNS_RESPSTATUS_GOOD
if at least one response was returned
.LP
.B GETDNS_RESPSTATUS_NO_NAME
if queries for the name yielded all negative responses
.LP
.B GETDNS_RESPSTATUS_ALL_TIMEOUT
if all queries for the name timed out
.LP
.B GETDNS_RESPSTATUS_NO_SECURE_ANSWERS
if only secure replies accepted (per context) and at least one response was received but no DNS responses were secure through DNSSEC

.LP
For a more detailed explanation of the response object see
.I libgetdns
(3)

.SH EXAMPLES

TBD

.SH FILES
.br
/etc/hosts
.br
/etc/resolv.conf

.SH SEE ALSO
.BR libgetdns (3),
.BR getdns_context (3), 
.BR getdns_free_sync_request_memory (3), 
.BR getdns_general (3), 
.BR getdns_address (3), 
.BR getdns_service (3),